Holding concentrate in a working bulk tank

[emericksmaple]

We are looking at installing a working bulk tank for next season. We will be concentrating to 15% - 16%. Does anyone know how cold we can go at that brix, before it will feeeze? I know the places that do high concentrate can go into the upper 20's.

[maple flats]

Check with Dr Tim, he gave that answer or formula before.

[DrTimPerkins]

Here you go. Approach the setpoint slowly. Thermometers and refrigeration can vary by a few degrees. Lower the temperature gradually. If slush starts to form, back off a little. An ice-cube in your bulk tank can ruin your day (or three).

freezepointsugar.JPG

[emericksmaple]

Thank you, Dr. Perkins

[upsmapleman]

My question is do you need to take it down to just above freezing or can you take it to say 35 degrees and hold it.

[DrTimPerkins]

You can do whatever you like, but the colder you can keep it the longer it will store.

[Bucket Head]

Dr. Tim,

Any suggestions on what temperature any given percentage of concentrate should be stored at? Did you experiment any with different percentages and temps. when you got your tank? A lot of RO's out there with different performance levels so there might be a "no hotter than" temperature folks could aim for with their refrigeration set ups.

Thanks.

Steve

[DrTimPerkins]

Hey Steve ... Not sure exactly what you're looking for, but sap/concentrate spoilage is a function of time, temperature, sugar concentration and initial microbial load. We have done studies on it, with the following general results:

- warm sap spoils faster than cold sap
- higher sap sugar spoils faster than lower sap sugar
- sap spoils more the longer it is left out
- if sap has a lot of microbes to start with, spoilage will be faster

The colder it is kept, the longer it will last, but there is no single setpoint that we can say after this it is bad. Somewhat depends upon the types of microbes in the sap and aeration to some degree as well. Best way is to think of it as milk....how long would you leave it out at a given temperature and still drink it? An hour at room temp...probably OK. A day at room temp....probably not.

The issue this week is likely to be sap souring in the lines even before it reaches the sugarhouse. We are going to segregate our sap into different tanks and do test boils to see how it is....if it gets bad, we'll dump it until after a good freeze and hope that a return to cold weather will flush out the lines.

[Shaun]

"Somewhat depends upon the types of microbes in the sap and aeration to some degree as well. "

Is aeration a good thing or bad thing? Does UVM run the agitator in the tank continuous, some or not at all?

[Bucket Head]

Dr. Tim,

I had not seen the chart you provided before with the freezing points of concentration. So I was wondering if there was a "not good enough" temp. for concentrates. Or put another way, for instance, 8-10% sap could be held safely at average refrigerator temps. but high concentration has to be held at far below 32 degrees. And that got me to thinking about my set up.
For the record and for comparison, I hold 10-12% concentrate at 34 degrees, which is the lowest setting on my tank. Not sure how or if I could get it to go lower, but I have had great results with this tank at these levels.

Steve